The States Reorganisation Act,1956
Section 11. Formation of a new Punjab State
As from the appointed day, there shall be formed a new Part A State to be known as the State of Punjab comprising the following territories, namely:-
(a) The territories of the existing State of Punjab; and
(b) The territories of the existing State of Patiala and East Punjab States Union;
And thereupon the said territories shall cease to form part of the said existing States of Punjab and Patiala and East Punjab States Union, respectively.